fix(uart): uart rx timeout validation with proper log message (espressif#11141)

* feat(uart): adds a function to calculate maximum valid rx timeout

* fix(uart): check uart rx timeout value and log an error msg

* fix(uart): changes log message to a more clear one

* ci(pre-commit): Apply automatic fixes

---------

Co-authored-by: pre-commit-ci-lite[bot] <117423508+pre-commit-ci-lite[bot]@users.noreply.github.com>

Author: SuGlider

cores/esp32/esp32-hal-uart.c

@@ -757,7 +757,11 @@ bool uartSetRxTimeout(uart_t *uart, uint8_t numSymbTimeout) {
   if (uart == NULL) {
     return false;
   }
-
+  uint16_t maxRXTimeout = uart_get_max_rx_timeout(uart->num);
+  if (numSymbTimeout > maxRXTimeout) {
+    log_e("Invalid RX Timeout value, its limit is %d", maxRXTimeout);
+    return false;
+  }
   UART_MUTEX_LOCK();
   bool retCode = (ESP_OK == uart_set_rx_timeout(uart->num, numSymbTimeout));
   UART_MUTEX_UNLOCK();
@@ -1382,4 +1386,24 @@ int uart_send_msg_with_break(uint8_t uartNum, uint8_t *msg, size_t msgSize) {
   return uart_write_bytes_with_break(uartNum, (const void *)msg, msgSize, 12);
 }
 
+// returns the maximum valid uart RX Timeout based on the UART Source Clock and Baudrate
+uint16_t uart_get_max_rx_timeout(uint8_t uartNum) {
+  if (uartNum >= SOC_UART_NUM) {
+    log_e("UART%d is invalid. This device has %d UARTs, from 0 to %d.", uartNum, SOC_UART_NUM, SOC_UART_NUM - 1);
+    return (uint16_t)-1;
+  }
+  uint16_t tout_max_thresh = uart_ll_max_tout_thrd(UART_LL_GET_HW(uartNum));
+  uint8_t symbol_len = 1;  // number of bits per symbol including start
+  uart_parity_t parity_mode;
+  uart_stop_bits_t stop_bit;
+  uart_word_length_t data_bit;
+  uart_ll_get_data_bit_num(UART_LL_GET_HW(uartNum), &data_bit);
+  uart_ll_get_stop_bits(UART_LL_GET_HW(uartNum), &stop_bit);
+  uart_ll_get_parity(UART_LL_GET_HW(uartNum), &parity_mode);
+  symbol_len += (data_bit < UART_DATA_BITS_MAX) ? (uint8_t)data_bit + 5 : 8;
+  symbol_len += (stop_bit > UART_STOP_BITS_1) ? 2 : 1;
+  symbol_len += (parity_mode > UART_PARITY_DISABLE) ? 1 : 0;
+  return (uint16_t)(tout_max_thresh / symbol_len);
+}
+
 #endif /* SOC_UART_SUPPORTED */

cores/esp32/esp32-hal-uart.h

@@ -116,6 +116,10 @@ void uart_send_break(uint8_t uartNum);
 // Sends a buffer and at the end of the stream, it generates BREAK in the line
 int uart_send_msg_with_break(uint8_t uartNum, uint8_t *msg, size_t msgSize);
 
+// UART RX Timeout (in UART Symbols) depends on the UART Clock Source and the SoC that is used
+// This is a helper function that calculates what is the maximum RX Timeout that a running UART IDF driver allows.
+uint16_t uart_get_max_rx_timeout(uint8_t uartNum);
+
 #ifdef __cplusplus
 }
 #endif